In USB2.0 and other high speed data links, a high speed receiver needs to detect a squelch condition when a differential voltage level on the data bus falls below a low threshold. A non-squelch also needs to be detected when the differential voltage level is above a high threshold. In USB2.0, the high threshold is 150 mV, and the low threshold 100 mV. Squelch detection is needed to determine whether the data transmitted on the bus is noise or is a valid signal.
It would be desirable to implement a circuit that performs squelch detection that may be suitable for a USB2.0, Firewire, Serial ATA, or other high speed bus environment.